Expansion joint for concrete structures



y 1940- F. L. KRUMHOLTZ EXPANSION JOINT FOR CONCRETE STRUCTURES Original Filed Feb. 25, 19:55 2 Sheets-Sheet 1 w? H Q. \U N July 16, 1940. F. KRUMHOLTZ EXPANSION JOINT FOR CONCRETE STRUCTURES Original Filed Feb. 25, 1955 2 Sheets-Sheet 2 Patented July 16, 1940 UNITED STATES EXPANSION JOINT FOR CONCRETE STRUCTURES Fred L. Krumholtz, Dayton, Ohio, assignor to Five-Way Expansion Joint 00., Chicago, Ill., a

corporation of Illinois Substitute for abandoned application Serial No.

8,009, February 25,

1935. This application December 14, 1936, Serial No. 115,861

12 Claims.

The invention relates to expansion-joints for use in roadways or other concrete structures or highways.

The objects of the invention are to provide: an expansion-joint for this use which is designed to be fabricated into an assembled unit for convenient and unitary installation in the roadway and comprises a hollow expansible structure, load-transfer members and load-distribution bars an improved expansion-joint comprising a hollow expansible structure which will be self-retaining on the sub-grade or bed during installation so that accessories for retaining the structure and load-transfer members in place during installation will be unnecessary; and an improved expansion-joint having a pair of loaddistribution bars which are spaced laterally apart on opposite sides of the hollow structure and are secured in the load-transfer members so that the labor necessary in tying or wiring the bars to said members will be saved; an expansion-joint in which the hollow supporting structure comprises a series of legs arranged end-to-end and secured together by a continuous top-strip.

Other objects of the invention and the various advantages and characteristics of the present expansion joint will be apparent from a consideration of the following detailed description.

The invention consists in the several novel features which are hereinafter set forth and are more particularly defined by the claims at the conclusion hereof.

In the drawings which accompany and form a part of this specification or disclosure and in which like numerals of reference denote corresponding parts throughout the several views:

Fig, 1 is a vertical transverse sectional view showing an expansion joint embodying one form of the invention in place between and in the contiguous slabs of a concrete roadway. Fig. 2 is a perspective of the hollow cap member of the joint. Fig. 3 is a perspective view showing the joint without the cap member for purposes of illustration. Fig. 3 is a perspective of one of the hollow leg sections of the joint. Fig. 4 is a perspective of one of the load transfer members and its yieldable supporting plates. Fig. 5 is a plan of a complete joint. Fig. 6 is a plan of a modified form of joint. Fig. 7 is a transverse sectional view of a second modified form of joint. Fig. 8 is a perspective of one of the supporting and closure plates between the legs of the joint of Fig. '7. Fig. 9 is a section on the line 99 of Fig. 7.

The joint which is shown in Figures 1 to 6 inclusive of the drawings constitutes the preferred embodiment of the invention. It is illustrated between a pair of roadway forming concrete slabs E0 on a sub-grade or bed 8 and serves to permit expansion and contraction of the slabs resulting from temperature changes. The joint comprises a hollow expansible structure in the form of a series of hollow legs is and I5 which are arranged in end-to-end relation and are upwardly convergent. Each of these legs M and i5 is formed of sheet metal and is U-shaped in cross-section and has its ends closed, as at IE, to prevent concrete or moisture from entering the chambers or spaces therein during pouring of the slabs II] in connection with formation of the roadway. The upper side margins of each leg is and I5 have outwardly extending flanges ll. The chambers in said legs permit the legs to contract and expand in response to expansion and contraction of the slabs H). The legs I4 and I5 constitute a substantially continuous hollow supporting structure. A longitudinally extending continuous inverted U-shaped cap-strip H serves to connect the hollow legs l4 and I5 and has an air chamber between its sides which permits expansion and contraction of the concrete slabs at the sides thereof. This cap strip H is also formed of sheet metal. The lower margins of the strip areextended transversely and outwardly from its sides to form flanges and these flanges are reverted or doubled back, as at 22, to form grooves l3 which receive, and in which are retained, the flanges I! of the hollow legs l4 and IS. A bituminous filler I9 is usually applied over the cap-strip II and between the adjacent slabs Ill of concrete. The outermost portions of the flanges on the cap-strip H are bent to form a bead H The latter form interlocks between the flanges and the concrete so that when the latter contracts it will draw the sides of the cap strip outwardly. The legs I4 and I5 are alternately arranged to extend to the opposite sides of the joint so that the lower ends of the alternating legs will be spread apart and converge upwardly to the cap-strip. This alternate arrangement renders the hollow structure self-retaining or so it will remain in place without stake pins, that is, other means to prevent the joint from tipping during pouring of the concrete for the slabs ID. A triangular plate [5 is secured to one end of each leg l4 and It to bridge the gap between the contiguous ends of the legs and to prevent the concrete from flowing from the slab at one side of the joint to the slab at the other. These plates are formed of thin metal.

Load-transfer members are provided between the slabs II] of concrete at the sides of the joint. These members comprise pairs of aligned tubes 20 which project outwardly from the sides of the legs I4 and I5 and are adapted for embedment in the slabs i0, and in addition comprise horizontally extending dowel rods 23 which extend transversely across the hollow structure and are formed of steel or any other suitable material. The ends of the dowel rods fit slidably within the tubes 2!] and hence the load transfer members serve efliciently and effectively to transfer load from the slab at one side of the joint to the slab at the other side of the joint. Each of the tubes 20 has its inner end welded to a plate 28 which normally lies approximately parallel to, and on the inside of, one of the walls of the contiguous leg of the hollow structure and is provided with a tongue 20 which fits in one of the grooves l3 0f the cap-strip H. The plates 20* are joined to the tongues 28* by curved bends 20 which permit the plates 29* to flex or move relatively to the walls of the legs. The flanges ll of the legs [4 and i5 are cut away, as at 20 so that the tongues 29"" will fit in the grooves l3 of the cap-strip in alignment with said flanges. The side walls of the legs are formed with openings extending downwardly from the cut-aways 20 These openings are normally closed by the plates 2!] and permit movement of the tubes 25! relatively to said walls. This exemplifies a construction in which the tubes of the load-transfer members are resiliently supported for movement independently of the side walls of the hollow legs, and so that flexing of said walls will not rupture them from their supports.

The inside of the tubes 20 or the outside of the dowel rods 23 is coated with lubricant, such as graphite, to prevent the rods from sticking in the tubes and so that the tubes at one side of the joint, when embedded in the concrete, can move relatively to the rods and the tubes at the other side of the joint. This insures freedom of movement between the tubes and the dowel rods during the life of the joint. The outer ends of tubes 20 are pressed together to close them so as to exclude concrete from the interior of the tubes during pouring of the slabs l0 and to retain the lubricant around the dowel rods 23.

In fabricating the joint, the flanges I? of the legs 14 and I5, are slipped endwise into the grooves iii in the cap-strip ll with the legs I4 and i5 alternated and their contiguous ends in abutting relation. In assembling the legs with the cap-strip, the tongues 20* on the tube-carrying plates 20 are placed in the cut-aways 26.

In addition to the hollow structure and the load transfer-members the joint comprises a pair of load-distribution bars 22. These bars are carried by the load-transfer members and extend through holes adjacent to the outer ends of the tubes 23 and outwardly of the ends of the dowel rods 23. Each bar 22 extends through a series or set of the tubes 28. After the legs M and Hi have been assembled and connected together by the cap-strip H the load-distribution bars 22 are passed through the holes in the outer ends of the tubes 20 and thereafter the outer ends of the tubes are pressed together to form closures. The sides of the legs it and I5 and the cap-strip ll permit the concrete slabs Hi to expand and contract from temperature changes. During this expansion and contraction there will be a sliding movement between the tubes 20 and the rods 23, and the tubes 2% which are embedded in the slabs can move inwardly independently of the side walls of the legs and the cap-strip. In addition to acting as distributing elements the bars 22 serve to maintain the load distribution members in a common horizontal plane during pouring of the concrete for the slabs H) and hence the-re is no likelihood of any one of the load transfer members being tilted or canted relatively to the other members. In

Fig. 6 of the drawings is illustrated a joint without load-distributing bars.

In Figs. 7 to 9 inclusive is illustrated a modified form of joint comprising a series of hollow legs 25 which are aligned with one another and are U-shaped in cross section. Each leg 25 has top flanges 26 fitting in grooves 2'! in the flanges 28 on an inverted U-shaped top-strip H Tubes 20 and bars 23 for load-distribution are supported by yieldable plates, as before described. In this form of the invention, the legs 25 have open ends and foot plates 30 of sheet metal are interposed between the ends of said legs to form closures therefor. The plates 30 are provided with flanges 3| which are adapted to slip into the grooves 21 of the cap-strip H between the ends of the flanges 26 on the legs 25. In assembling this form of the invention, the sections 25 are successively slipped into the grooves 21 on the top-strip H with the plates 38 interposed between their contiguous ends. Said plates 3|] have downwardly divergent edges and form feet which are adapted to rest on the bed and support the joint without stake pins or anchors.

The invention exemplifies an expansionjoint which comprises a hollow supporting structure, load-transfer members, and load-distribution bars, and can be fabricated and assembled for unitary installation on the sub-grade or bed of the roadway or assembled on the job; also a joint in which the load-transfer members consist of tubes with closed ends and dowel bars in the tubes; also a joint in which hollow upwardly convergent legs support the hollow capstrip so the joint will be self-retained when placed on the sub-grade or bed of the roadway; also a joint in which the load-transfer members comprise tubes which are adapted for embedment in the slabs and are movable independently of the side walls of the hollow legs to permit relative movement between the tubes and side walls; also a joint which includes load-distribution bars, fixedly secured in and carried by the tubes of the loadtransfer members; and also an expansion-joint of this character which can be produced at a low cost.

The invention is not to be understood as restricted to the details set forth, since these can be modified within the scope of the appended claims, without departing from the spirit and scope of the invention.

The subject matter of the present application is the same as that forming the subject matter of applicants abandoned application, filed February 25, 1935, Serial No. 8009.

Having thus described the invention, what I claim as new and desire to secure by Letters Patent is:

1. In a joint for contiguous concrete slabs, the

' combination of an elongated hollow supporting structure adapted to be positioned between the contiguous faces of the slabs and consisting of a series of separately formed alternately arranged upwardly convergent hollow U shaped legs arranged end to end and having their lower ends closed and adapted to rest on a bed under the slabs, and a separately formed hollow conti11uous upper strip connecting the legs together and having a closed top for closing the top portion of the legs and outwardly extending side flanges, and load transfer members comprising a series of laterally spaced alined pairs of tubes associated respectively with, and projecting outwardly from the side walls of the legs and adapted for embedment in and to be bonded to the slabs and connected to and supported from the side flanges of the upper strip, and dowel rods extending through the structure and having the ends thereof fitting slidably in said tubes.

2. In a joint for contiguous concrete slabs, the combination of an elongated hollow supporting structure adapted to be positioned between the contiguous faces of the slabs and consisting of a series of separately formed hollow U-shaped legs arranged in end to end relation and having their lower ends closed and adapted to rest on a bed under the slabs and a separately formed hollow continuous upper strip connecting the legs together and having a closed top for closing the top portions of the legs and outwardly extending side flanges, and a series of separately formed laterally spaced alined pairs of tubes associated respectively with, and projecting outwardly from the side walls of the legs and adapted for embedment in and to be bonded to the slabs, flexible supporting plates for the tubes connected to and supported from the side flanges of said upper strip, and dowel rods extending through the structure and having the ends thereof fitting slidably in the tubes.

3. A joint for contiguous horizontally extending concrete slabs, comprising an elongated supporting structure adapted to be positioned between the contiguous faces of the slabs and consisting of a series of separately formed alternately arranged hollow upwardly convergent legs having closed lower ends and adapted to retain the structure in an upright position on a bed beneath the slabs, and a hollow cap strip connecting and serving to close the top portions of the conver-- gent legs, and separately formed load transfer members projecting outwardly from the sides of the legs and adapted for embedment in said slabs.

4. A joint for contiguous concrete slabs, comprising an elongated hollow structure adapted to be positioned between the slabs and consisting of a series of separately formed alternately arranged upwardly convergent hollow U-shaped legs arranged. end-to-end and having their lower ends closed and adapted to rest on a bed under the slabs, and a separately formed hollow continuous upper strip connecting the legs together and having a closed top for closing the top portions of said legs.

5. In a joint for contiguous concrete slabs, the combination of an elongated hollow structure adapted to be positioned between the slabs and comprising a series of separately formed upwardly convergent hollow legs arranged end-to-end and having their lower ends closed and adapted to rest on a bed beneath the slabs, and a separately formed hollow continuous upper member connecting the legs together and serving to close the top portions of said legs, and load transfer members extending outwardly and formed separately from the sides of the legs and adapted for embedment in the slabs.

6. A joint for contiguous concrete slabs, comprising an elongated supporting structure adapted to be positioned between the slabs and consisting of a series of separately formed hollow U-shaped legs arranged end-to-end, the alternate legs having their lower ends disposed on opposite sides of the structure and extending obliquely upward with their upper ends aligned, and a continuous longitudinally extending separately formed topstrip connecting and serving to close the top portions of the legs.

'7. In a joint for contiguous concrete slabs, the combination of a hollow supporting structure adapted to be positioned between the slabs and comprising a series of hollow U-shaped legs ar ranged end-to-end and a continuous separately formed cap-strip whereby the legs are connected together, and a series of laterally spaced load transfer members extending outwardly and formed separately from the sides of the legs and adapted for embedment in the slabs.

8. A joint for contiguous concrete slabs, comprising a supporting structure adapted to be positioned between the slabs and consisting of a series of separately formed alternately arranged upwardly convergent U-shaped sections arranged end-to-end and having their bottoms and contiguous ends closed, and a contiguous cap-strip whereby the legs are connected together and the upper ends thereof are closed.

9. In a joint for contiguous concrete slabs, the combination of an elongated supporting structure adapted to be positioned between the slabs and comprising a series .of U-shaped legs arranged end-to-end, a continuous cap-strip whereby the sections are connected together, tubes projecting outwardly from the sides of the legs and adapted to be embedded in the slabs, and a pair of load distributing bars for embedment and transverse disposition in the slabs positioned one on one side and one on the other side of, and in parallel relation with respect to, the structure and carried by the outer ends of said tubes.

10. In a joint for contiguous concrete slabs,

the combination of an inverted hollow U-shaped strip adapted to be positioned between the slabs and having flanges projecting from opposite sides at its lower end with reverted positions to form grooves, and a series of separately formed alternately arranged upwardly convergent U-shaped legs arranged in end-to-end relation beneath the strip and having flanges extending outwardly from their upper ends and fitting in the flange formed grooves of the strip, and load-transfer members projecting from the sides of the legs and adapted for embedment in the slabs.

11. A joint for contiguous concrete slabs comprising an elongated hollow structure adapted to fit between the slabs and consisting of an inverted U-shaped cap-strip, a series of alternately arranged upwardly convergent U-shaped legs disposed beneath the cap-strip and arranged in end-to-end relation, interfitting flanges between the bottom margins of the side walls of the capstrip and the top margins of the side walls of the legs, and plates fitting between and serving to close the contiguous ends of the legs and having their upper ends held in certain of said flanges.

12. A joint for contiguous concrete slabs, comprising an elongated hollow structure adapted to be positioned between the slabs and consisting of a series of separately formed, alternately arranged upwardly convergent open ended hollow U-shaped legs arranged end to end and having their lower ends closed and adapted to rest on a bed under the slabs, a separately formed hollow continuous upper strip connecting the legs together and having a closed top for closing the top portions of said legs, and plates fitting between and serving to close the contiguous ends of the legs.

FRED L. KRUMHOLTZ. 

